Ship davit



W. L. MAPPIN Jan. 28, 1947.

SHIP DAVIT Filed Jan. 20, 1944 2 Sheets-Sheet l Jan. 28, 1947.

W. L. MAPPIN SHIP DAVIT Filed Jan. 20, 1944 2 Sheets-Sheet 2 QR w m a m w M, a w

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Patented Jan. 28, 1947 OFFICE SHIP DAVIT Walter Levison Mappin, New Westminster, British Columbia, Canada Application January 20, 1944, Serial No. 518,930

9 Claims.

My invention relates to improvements in ships davits.

Hitherto when a ship in distress has had a list of more than a few degrees it has been found extremely diflicult and in most cases quite impossible to launch the life boats from the davits mounted on the high side of the ship. The main reason for this is that to swing the boat out over the side required the swinging of the davit up and over the centre of horizontal axis of the davits. Obviously any increase in the angle of the list increased the lift necessary to carry the boat over centre. To obviate this dificulty to som extent, boats were overhung from the axis of the davits and were allowed to overhang the ships side, which has resulted, during war time, in the boats being blown up from torpedo explosion where the blast struck up the ships side and struck the overhanging side of the life boat. This damage would result in the life boats on the low side of the ship being destroyed, leaving only those on the high side for life saving purposes and frequently none of these could be launched with the result that the life rafts alone could be utilized.

The objects of the present invention are to provide means whereby the boats can be carried entirely inboard, whereby the boat is carried outboard clear of the ships side entirely by gravity at any list at which a person can stand on the deck of the ship. Other objects will appear as the specification proceeds.

Referring to the drawings:

Fig. 1 is an end elevation of the invention part in section.

Fig. 2 is a rear elevation.

Fig. 3 is a view showing the davit outwardly swung to lower the boat, with the ship having a thirty degree list.

Fig. 4 is an elevational view of the gear cover showing hand crank and brake.

Fig. 5 is a plan view showing the crosshead.

Fig. 6 is a diagrammatical view showing a simplified means of control for small ships.

In the drawings like characters of reference indicate corresponding parts in each figure.

The numeral I indicates a portion of a ship in which 2 is the side wall and 3 the deck. The numeral 4 indicates generally one of the davits, which obviously would be in pairs and may be coupled together for simultaneous operation.

' Each davit 4 has a frame 5 consisting of spaced sides 6, having bearers 1, legs 8 and horizontal Slidably mounted between the bearers I is a rack ll which is supported on which is of any suitable type.

. 2 rollers l2 and is fitted at opposite ends with sheaves I3 and It. The rack l l is secured in a normal position of rest as shown in Figure l with its forward sheave l3 forward of the front leg 8 and is adapted to move rearwardly in launching until said sheave is to the rear of said front leg as shown in Figure 3. A crosshead I6, see Figure 5, is slidably mounted between the guides 9 and is formed with a U-shaped member I! through which a shaft [8 extends. The shaft is fitted with rollers l9 at its ends and forms a bearing pin for a davit member 20.

The davit member 20 consists of a quadrant 22 having gear teeth 23 which engage corresponding teeth 24 on the rack I I. 'The quadrant 22 is surmounted with a curved davit arm 26 which is fitted on opposite sides with sheaves 28, 29 and 29A and sheaves 3B and is equipped at its outer extremity with a pair of fall blocks 3,2 from which a life boat 34 is suspended. The rope or falls 35 from which the boat 34 is supported is anchored to an eye 36 adjacent the front of the frame-5, see Figures 1, 2 and 3, and leads around the sheaves 29 and 3|], through the fall blocks 3'2 and around the second sheaves 30 and 29A, thence through a block 38 to a suitable cleat or other fastening, not shown.

The boat is normally held in an inboard position by a cinch rope 39 which extends from the upper extremity of the davit arm as at 40, passing under the boat and over the sheave 28 to an eye 42. Interposed in the cinch rope between the eye 42 and the sheave 28 is a snatch hook 43 for the purpose of providing a quick means for releasing the boat from its inboard position. An eye 44 is provided on the rear of the davit arm 26 to which is permanently secured a short cable 45. This short cable is also connected normally to the snatch hook 43, so that when the snatch hook is opened the davit member 20 is released for movement as required.

A housing 50, see Figures 2 and 4, is formed partly within the frame 5 in which a compound operating gear train 5| is mounted. The operating gear preferably consists of a shaft 52 having a crank and handle 53 and 54, a drive pinion 55, a brake drum 56 in which is included a centrifugal governor indicated by the numeral 51 The pinion drives a gear 68' to which a pinion 6| is coupled, both of which are mounted upon a shaft 62, the pinion 6| in turn drives a gear 63 upon a final drive shaft 64 which is also fitted with a cable drum 65. The brake drum is fitted with a brake band 68 which is actuated by a brake lever 69 through a brake shaft 10. The brake lever is of suflicient weight to apply the brake and maintain the operating gear at rest and is provided with a chain suspended pin 12 which may be inserted into a hole 13 in the frame 5 to support the lever 69 in raised position to keep the brake in the off position.

The crosshead i6 is moved along its guide by cables 15 and 16, the cable 15 extends from the forward end of the carriage around a sheave TI on the frame 5, thence around the sheave l3 and onto the cable drum 65, and the cable 16 extends from the rear end of the crosshead l6, around a sheave I8, thence around the sheave I4 and onto the cable drum.

In the modification, no compound gearing is shown for controlling the davit, a single rope only is necessary to effectively control the device since lighter weight boats and equipment make the automatic controlling mechanism unnecessary. The sliding rack of the modification is indicated by the numeral 8|, the davit member 82 is provided with a quadrant 83 and a fulcrum 84 which slides along the guides 85 as above described. A single rope 81 passes through a sheave tackle 88 extending between the inner end of the frame 89 and the outer or rear end of the rack 8|, thence through another sheave tackle 90 extending between a bracket 9| projecting inboard of the frame and the fulcrum 84 of the quadrant 83. The free end of the rope 81 is normally fastened to a bollard 92 around which it may be snubbed when paying out the rope to bring a boat outboard from its davits.

It will be obvious that with the ship on an even keel or at an incline of even thirty degrees as shown in Figure 3, the centre of gravity of the davit member and the boat is such as to urge the davit member 2!] to swing outboard.

In lowering a boat the snatch hook 43 is opened, thus releasing the davit member 20 from its normal position and allowing the boat 34 to hang vertically from its falls, the brake lever 69 is then raised, releasing the brake band 68, thus allowing the weight of the boat to exert a tensioned strain on the fall rope 35 between the sheave 29 and the eye 36 adjacent the front ofthe frame 5. The strain so exerted pulls the davit arm 26 over until its upper extremity reaches the point S, see Figure 1, this tensional strain also starts the operating gear train BI and through slackening the strain on the cable 16 and imposing a corresponding strain on the cable 15 allows the rack l I to recede to the position shown in Figure 3, The rack II is of such weight that as the ships deck takes a list it will tend to slide downwardly and the effort so provided is such as to swing the quadrant about the crosshead even without the tensional strain on the rope 35. As soon as the rack reaches its innermost position the motion of the gear train 5| will cause the drum to wind more of the rope 15 onto the drum 65 and allow the crosshead [6 to travel forwardly along the guides 9 with the quadrant rolling forwardly along the rack II. The path of travel of the upper extremity of the davit arm from normal position to that indicated at T where a boat could be launched over the side of the ship when listed to forty-five degrees, is along the dotted line U, In the travel of the arm from the point 5 to the point T a change takes Place in the combined length of rope between the block 38 and the sheave 29A and the eye 36 in that it becomes greater than the combined length of the same rope between these points when the arm'is at the position S. This elongation shortens the distance between the blocks 22 or raises the boat slightly with respect to the extremity of the arm and causes, in effect, a braking action on the swing of the arm and enables it to be stopped with less effort on the brake lever 69.

In operating the arm 82 in the modification shown diagrammatically in Figure 6, slackening of the rope 92 will first allow the tackle 88 to extend and permit the rack to run rearwardly, further slackening will allow the quadrant to roll forwardly along the rack to carry the boat overside. Hauling in of the rope first rolls the quadrant inwardly and then moves the rack outwardly to restore the davit to normal position.

What I claim as my invention is:

1. A ships davit comprising a frame with an outboard and an inboard end, a davit member pivotally mounted intermediate its ends in a crosshead, a guide between the ends of the frame, said crosshead being adapted for movement in launching to move along the guide towards the outboard end of the frame, and means actuated by an inboard list to the frame for urging the upper end-of said davit member to swing about the crosshead towards the outboard end of said frame, and the lower end of said davit member to move. towards the inboard end of said frame and means for restraining the movement of the davit member.

2. A ships davit comprising a frame with an outboard and an inboard end, a davit member pivotally and slidably mounted within the frame, said member having a quadrant within the frame and a davit arm extending above the frame and having an overhanging portion adapted to support one end of a boat, a rack within the frame having engaging contact with the quadrant, said rack having sliding movement under the quadrant to impart initial swinging movement to the davit member, and means for preventing the sliding movement of the member.

3. A ships davit comprising a frame with an outboard and an. inboard end, a davit member pivotally and slidably mounted within the frame, said member having. a quadrant Within the frame and a davit arm extending above the frame and having an overhanging portion adapted to support one end of a boat, a rack within the frame having engaging contact with the quadrant, said rack having sliding movement under the quadrant to impart initial swinging movement to the davit member and means for preventing the sliding movement of. the member, and means for releasing the member to permit the quadrant to roll along the rack.

4. A ships davit comprising a frame with an outboard and an inboard end, a davit member pivotally and slidably mounted within the frame, said member having a quadrant within the frame and a davit arm extending above the frame and having an overhanging portion adapted to support one end of a boat, a rack within the frame having engaging. contact with the quadrant, said rack having sliding movement under the quadrant to impart initial swinging movement to the davit member and means for preventing the sliding movement of the member, means for releasing the member to permit the quadrant to roll along the rack, and means for automatically controllin the rolling movement of the quadrant.

5. A ships davit comprising a frame with an outboard and an inboard end, a davitmember pivotally mounted within the frame, a pair of blocks adapted to support a load from the upper end of the davit member, a, fall rope anchored ad jacent the outboard end of the frame, said rope leading along the davit member, through the blocks and to. a normally fixed point adjacent the rear of the frame whereby the load tends to swing the upper end of the davit member outboard for the initial portion of its movement.

6. A ships davit comprising a frame with an outboard and an inboard end, a davit member pivotally mounted within the frame, a pair of blocks adapted to support a load from the upper end of the davit member, a fall rope anchored adjacent the outboard end of the frame, said rope leading along the davit member, through the blocks and to a normally fixed point adjacent the rear of the frame whereby the load tends to swing the upper end of the davit member outboard for the initial portion of its movement and to restrain the swinging movement of the davit member in another portion of said movement.

7. YA ships davit comprising a frame having an outboard and an inboard end, a davit member consisting of a quadrant and a davit arm, said frame having an endwise slidable rack in its base and guides thereabove, a crosshead slidable in the guides, said davit member being pivotally mounted in the crosshead and having its quadrant in driving engagement with the rack, means for holding the davit member and the rack in normal positions of rest, said means on being re- 6. leased being adapted to first permit the rack to move to give an initial tilt to the davit member and subsequently to permit the quadrant to roll upon the rack.

S. A ships davit comprising a frame having an outboard and an inboard end, a davit member consisting of a quadrant and a davit arm, said frame having an endwise slidable rack in its base and guides thereabove, a crosshead slidable in the guides, said davit member being pivotally mounted in the crosshead and having its quadrant in driving engagement with the rack, means for holding the davit member and the rack in normal positions of rest, said means on bein released being adapted to first permit the rack to move to give an initial tilt to the davit member and subsequently to permit the quadrant to roll upon the rack and a governor to control the movement of said rack and quadrant.

9. .A ships davit comprising a frame with an outboard and an inboard end, a davit member mounted formovement within the frame, said davit member having a pivot intermediate its length and slidable lengthwise of the frame, means for rocking the davit member upon its pivot in one movement with the pivot remaining in a fixed axial position and means for rockin the davit upon its pivot and movin the pivot laterally within the frame in another movement.

I WALTER LEVISON MAPPIN. 

